How Many Atoms Are in an H2O Molecule?

Toshiro Shimada/Moment/Getty Images

A water molecule is composed of three atoms. There are two atoms of hydrogen (H2) and one atom of oxygen (O) in each molecule of water. Water molecules also contain four lone pair electrons on the oxygen atom. This allows each water molecule to take on a bent geometrical form.

Water is a highly polar molecule due to its negative electron pairs on the oxygen atom. Each hydrogen atom is slightly positive, but as a whole, water molecules have a negative dipole pointed towards the electron cloud above the oxygen molecule. Due to water’s polarization, it can interact with itself and form strong bonds. Water molecules interact with each other via hydrogen bonds in its gas, liquid and solid forms.